The thermal degradation of blends of poly(vinyl
chloride) ( PVC ) with poly(vinyl acetate) (PVA), and
two ethylene-vinyl acetate copolymers containing 70
weight percent vinyl-acetate (EVA70) and 45 weight
percent vinyl acetate (EVA45) were studied by
thermogravimetric analysis and direct-pyrolysis mass
spectrometry. The PVC, PVA, EVA45 and EVA70 degrade
in two-step processes for each polymer. The PVA/PVC ,
EVA45/PVC and the EVA70/PVC blends do show some inter
action during the first step of the degradation process
while the respective second steps are unaffected. The
acid produced by the degradation of one polymer causes
accelerated loss of the other acid in the blend. The
extent of the interaction is a function of the
miscibility of the blends.